Leaps and bounds
Jul. 3rd, 2011 21:58![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
torquillI spent most of today assembling the frame for the windmill. For those of you unaware of the current status of that project, it's morphed into an omnidirectional spindle design, using a few key parts of the old assembly. Most of it is new, however, including a six foot spindle constructed of two bicycle wheels and four blades of aluminum flashing. It still drives a bicycle chain, connected to an intermediate hub and finally a car alternator, giving me a maximum ratio of 33:1. I can gear it down if I need to, though I think the speed should be fine; load will be fine-tuned by means of manipulating the field current on the alternator.
I have all the parts now, and the first piece to build was the wooden frame. It's just two-by-fours in a flat vertical rack arrangement, with legs extending out two feet on either side (it's basically an H when viewed from above). I drilled the metal braces and put in carriage bolts for easy assembly, because there's only so many times you can sink a screw into the same hole... I want this to hold up for several years at least, with setup and takedown several times each year. It seems quite solid, enough that I can safely stand on the lower rung of the rack and shake it back and forth in various directions. There's still a little wiggle, but the guywires should take care of that without a need for crossbracing.
The heaviest part of the assembly is the alternator, of course, and it's mounted on the base; I can pick up the frame easily (it's maybe 20 pounds) and the spindle should be about 15 pounds. Having the greatest weight at the bottom will help with stability, and the whole shebang should weigh in at 75 pounds or so, which is quite light enough to live on the roof of the rig. Once we cinch it down with guywires to the corners of the roof to deal with wind resistance, I expect it to be quite stable.
What we'll get out of it electrically remains to be seen. I'll get *something*, assuming the spindle will easily freewheel and catches some wind... the blessing of a car alternator is that it puts out 13.8V regardless, no matter how small a current that makes. If I have to take down the field current on the alternator to get the thing to turn in moderate winds, I'll still get a nice trickle of juice to keep the batteries topped up -- we use very little power at the Burn, normally, and if we have a heavy drain for some reason, we'll run the generator instead. So I expect a good return, even if it doesn't generate what most people would call a lot of power. I confess to some curiosity about its potential output, nonetheless.
This design has the blessing of being made out of freely available parts, most of them relatively cheap as major projects go... the frame cost about $50 in lumber and hardware, the alternator was $30, I got enough flashing for $30 to make two 6' spindles, and the bike parts can be had almost for free. The hardest bits to get were the mounts for the axles, which I scrounged at a junkyard (spare tire mounts), but those could be made out of steel sheet metal easily enough. (Maybe I'll fashion something out of one of the scrap computer cases we have around here if I need another.) The hardest technique was welding a gear hub to the alternator, something anybody with a steady hand and a MIG welder can do in a few minutes. If the windmill really works out, I'll see if I can find time to document it for Instructables or something.
We need to have it testable by the end of the month, which looks eminently possible. Wish me luck.
I have all the parts now, and the first piece to build was the wooden frame. It's just two-by-fours in a flat vertical rack arrangement, with legs extending out two feet on either side (it's basically an H when viewed from above). I drilled the metal braces and put in carriage bolts for easy assembly, because there's only so many times you can sink a screw into the same hole... I want this to hold up for several years at least, with setup and takedown several times each year. It seems quite solid, enough that I can safely stand on the lower rung of the rack and shake it back and forth in various directions. There's still a little wiggle, but the guywires should take care of that without a need for crossbracing.
The heaviest part of the assembly is the alternator, of course, and it's mounted on the base; I can pick up the frame easily (it's maybe 20 pounds) and the spindle should be about 15 pounds. Having the greatest weight at the bottom will help with stability, and the whole shebang should weigh in at 75 pounds or so, which is quite light enough to live on the roof of the rig. Once we cinch it down with guywires to the corners of the roof to deal with wind resistance, I expect it to be quite stable.
What we'll get out of it electrically remains to be seen. I'll get *something*, assuming the spindle will easily freewheel and catches some wind... the blessing of a car alternator is that it puts out 13.8V regardless, no matter how small a current that makes. If I have to take down the field current on the alternator to get the thing to turn in moderate winds, I'll still get a nice trickle of juice to keep the batteries topped up -- we use very little power at the Burn, normally, and if we have a heavy drain for some reason, we'll run the generator instead. So I expect a good return, even if it doesn't generate what most people would call a lot of power. I confess to some curiosity about its potential output, nonetheless.
This design has the blessing of being made out of freely available parts, most of them relatively cheap as major projects go... the frame cost about $50 in lumber and hardware, the alternator was $30, I got enough flashing for $30 to make two 6' spindles, and the bike parts can be had almost for free. The hardest bits to get were the mounts for the axles, which I scrounged at a junkyard (spare tire mounts), but those could be made out of steel sheet metal easily enough. (Maybe I'll fashion something out of one of the scrap computer cases we have around here if I need another.) The hardest technique was welding a gear hub to the alternator, something anybody with a steady hand and a MIG welder can do in a few minutes. If the windmill really works out, I'll see if I can find time to document it for Instructables or something.
We need to have it testable by the end of the month, which looks eminently possible. Wish me luck.
